1. Field of the Invention
The present invention relates to a network in which a plurality of electronic devices are connected through a high-speed serial bus (to be referred to as an IEEE 1394 bus hereinafter) or the like conforming to IEEE 1394 to perform communication among these electronic device and, more particularly, to a method and apparatus being capable of coping with a case in which the transmission data formats of a transmission-side device and a reception-side devices have mismatching in data transmission.
2. Description of the Related Art
A network for connecting electronic devices (to be referred to as devices hereinafter) such as a digital video cassette recorder, a digital still camera, a personal computer, a printer, and the like to each other through an IEEE 1394 bus to perform communication among these devices is conceivable.
In the network (to be referred to as an IEEE 1394 network) in which the plurality of devices are connected through the IEEE 1394 bus, transmission of data or a control signals is performed by time sharing multiplexing every predetermined communication cycle. As forms of communication in one communication cycle, the form of isochronous (to be referred to as Iso hereinafter) communication for transmitting video data, audio data, or the like on real time and the form of asynchronous (to be referred to as Async hereinafter) communication for occasionally transmitting a control signal such as an operation control command, a connection control command, or the like of a device as needed are known.
When print data supply device on an IEEE 1394 network supplies print data to a printer device to instruct the printer device to perform a print operation, the print data supply device must prepare and transmit data according to a data format in which the printer device can perform reception and printing.
The print data supply device must change the format of print data to be transmitted depending on a printer device serving as a print data destination. When a plurality of print data supply devices are connected to a network, all these devices must have functions for converting print data formats. As a result, the same functions are located at a plurality of positions on the network, and the resources are minimally used.
When the print data supply device cannot transmit data according to a data format in which the printer device can perform reception and printing, the printer device cannot print designated data disadvantageously.
The present invention has been made in consideration the conditions, and has as its object to provide a method and apparatus in which, when a data transmission device and data reception device are connected to an IEEE 1394 network, when the data reception device cannot cope with a data format in which the data transmission device can output data, the format of data to be transmitted is converted into an appropriate format, and the data is transmitted to the data reception device.
A device according to the first aspect of the present invention includes: acquisition means for acquiring data format information of data which can be processed by a first electronic device on a network and data format information of data which can be processed by a second electronic device on the network; decision means for deciding, on the basis of the acquired data format information, whether the data which can be processed by the first electronic device can be processed by the second electronic device or not; searching means for, if it is decided by the decision means that the data which can be processed by the first electronic device cannot be processed by the second electronic device, searching for an electronic device which can convert the data which can be processed by the first electronic device into the data having a format which can be processed by the second electronic device; and control means for, when the electronic device which can convert the data which can be processed by the first electronic device into the data having the format which can be processed by the second electronic device is detected by the searching means, controlling the first electronic device to output data to the detected electronic device and controlling the detected electronic device to convert the data and to output the data to the second electronic device.
An electronic device according to the second aspect of the present invention on a communication network having a bus and a plurality of electronic devices connected to the bus, including: means for checking a function mounted on an electronic device on the network; means for instructing and controlling the other device on the network to transmit data, and means for holding the information of the format of convertible data.
An electronic device according to the third aspect of the present invention on a communication network having a bus and a plurality of electronic devices connected to the bus, including: inputting means which receives a control signal from another device; means for converting the format of data transmitted through the bus; and means for holding the information of the format of convertible data.
A first data communication method according to the present invention including: the acquisition step of acquiring data format information of data which can be processed by a first electronic device on a network and data format information of data which can be processed by a second electronic device on the network; the decision step of deciding, on the basis of the acquired data format information, whether the data which can be processed by the first electronic device can be processed by the second electronic device or not; the searching step of, if it is decided in the decision step that the data which can be processed by the first electronic device cannot be processed by the second electronic device, searching for an electronic device which can convert the data which can be processed by the first electronic device into the data having a format which can be processed by the second electronic device; and the control step of, when the electronic device which can convert the data which can be processed by the first electronic device into the data having the format which can be processed by the second electronic device is detected by the searching step, controlling the first electronic device to output data to the detected electronic device and controlling the detected electronic device to convert the data and to output the data to the second electronic device.
In a second data communication method according to the present invention for performing data communication on a communication network having a bus and a plurality of devices connected to the bus, a controller acquires the information a transmittable data format of a source device and the information of receivable data format of a destination device, and determines a transmission data format on the basis of the information, instructs the source device to perform data communication by the determined data format, and, when the transmittable data format of the source device cannot be received by the destination device, the controller determines a transmission data format with reference to a data format which can be converted by a format converter connected to the bus and having a data format converting function and instructs the source device to transmit data to the format converter, and the format converter which receives the data transmits data to the destination device.
A system according to the present invention includes a third electronic device for acquiring data format information of data which can be processed by a first electronic device on a network and data format information of data which can be processed by a second electronic device on the network, and the third electronic device has: decision means for deciding, on the basis of the acquired data format information, whether the data which can be processed by the first electronic device can be processed by the second electronic device or not; searching means for, if it is decided by the decision means that the data which can be processed by the first electronic device cannot be processed by the second electronic device, searching for an electronic device which can convert the data which can be processed by the first electronic device into the data having a format which can be processed by the second electronic device; and control means for, when the electronic device which can convert the data which can be processed by the first electronic device into the data having the format which can be processed by the second electronic device is detected by the searching means, controlling the first electronic device to output data to the detected electronic device and controlling the detected electronic device to convert the data and to output the data to the second electronic device.
A recording medium according to the present invention includes a program for performing communication recorded thereon, and the program realizes: the acquisition step of acquiring data format information of data which can be processed by a first electronic device on a network and data format information of data which can be processed by a second electronic device on the network; the decision step of deciding, on the basis of the acquired data format information, whether the data which can be processed by the first electronic device can be processed by the second electronic device or not; the searching step of, when it is decided in the decision step that the data which can be processed by the first electronic device cannot be processed by the second electronic device, searching for an electronic device which can convert the data which can be processed by the first electronic device into the data having a format which can be processed by the second electronic device; and the control step of, when the electronic device which can convert the data which can be processed by the first electronic device into the data having the format which can be processed by the second electronic device is detected by the searching step, controlling the first electronic device to output data to the detected electronic device and controlling the detected electronic device to convert the data and to output the data to the second electronic device.
In the present invention, at a certain point of time, a device for transmitting data on a network is defined as a source device, and a device for receiving data and performing a process is defined as a destination device. A device for instructing and controlling a device connected to the network to perform data transmission is defined as a controller. A format converter having a data format converting function may be connected to a bus as a device independently of the source device, the destination device, and the controller.
Transmission of data from the source device to the destination device is performed by an instruction from the controller. The source device has a list of transmittable data formats as device information, and the destination device has a list of receivable and processible data formats as device information.
When the controller instructs the source device to perform data transmission from the source device to the destination device, the controller acquires the information of a transmittable data format of the source device and the information of a receivable data format of the destination device, determines a data format being appropriate to transmission on the basis of the information, and instructs the source device to perform data transmission to the destination according to a designated format.
When the appropriate format cannot be detected, the controller determines a data format for transmission of the source device and a data format for reception of the destination device with reference to data format information which can be changed by a format converter, and the controller instructs the source device to transmit data to the format converter in the data format. The format converter which receives the data converts data format into a format which can be received by the destination device, and transmits the data to the destination device.